U.S. patent number 6,986,833 [Application Number 10/272,011] was granted by the patent office on 2006-01-17 for process for fractionating water-containing crude amine mixtures from amine synthesis.
This patent grant is currently assigned to BASF Aktiengesellschaft. Invention is credited to Aurelie Alemany, Stefan Rittinger, Heinz Rutter, Willi Schmidt, Mark Wehinger, Andreas Wolfert.
United States Patent |
6,986,833 |
Wolfert , et al. |
January 17, 2006 |
**Please see images for:
( Certificate of Correction ) ** |
Process for fractionating water-containing crude amine mixtures
from amine synthesis
Abstract
An amine-containing mixture containing one or more amines,
water, low-boilers and optionally high-boilers is fractionated by a
process having the steps (iii) and (iv) and optionally the steps
(i), (ii) and (v): (i) a (first) low-boiler fraction is separated
off from the amine-containing mixture by distillation, (ii) a
(first) high-boiler fraction is separated off from the
amine-containing mixture by distillation, (iii) the
amine-containing mixture is extracted with sodium hydroxide
solution, producing an aqueous, sodium-hydroxide-containing first
phase and an aqueous-organic, amine-, (further) low-boiler- and
possibly (further) high-boiler-containing second phase, (iv) the
aqueous-organic second phase, is distilled, producing essentially
anhydrous amine as bottom-phase take off or sidestream takeoff in
the stripping part of the distillation column, an amine/water
azeotrop as sidestream takeoff in the enrichment part of the column
and a (further) low-boiler fraction as overhead takeoff, and
recycling the amine/water azeotrop to the extraction step (iii),
(v) the essentially anhydrous amine is further purified of
fractionated.
Inventors: |
Wolfert; Andreas (Bad Rappenau,
DE), Rutter; Heinz (Hochdorf-Assenheim,
DE), Rittinger; Stefan (Pahang, MY),
Wehinger; Mark (Ludwigshafen, DE), Alemany;
Aurelie (Mannheim, DE), Schmidt; Willi
(Ludwigshafen, DE) |
Assignee: |
BASF Aktiengesellschaft
(Ludwigshafen, DE)
|
Family
ID: |
7704135 |
Appl.
No.: |
10/272,011 |
Filed: |
October 17, 2002 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20030089591 A1 |
May 15, 2003 |
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Foreign Application Priority Data
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Oct 30, 2001 [DE] |
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101 53 411 |
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Current U.S.
Class: |
203/14; 203/43;
203/78; 203/80; 203/99; 203/DIG.19; 564/497 |
Current CPC
Class: |
C07C
209/86 (20130101); C07D 207/04 (20130101); C07D
211/04 (20130101); C07D 295/03 (20130101); C07C
209/86 (20130101); C07C 211/04 (20130101); C07C
209/86 (20130101); C07C 211/08 (20130101); Y10S
203/20 (20130101) |
Current International
Class: |
B01D
3/14 (20060101); C07C 209/84 (20060101) |
Field of
Search: |
;203/14,DIG.19,37,43,45-46,78-80,91-98 ;564/497,499 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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27 23 474 |
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Dec 1977 |
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DE |
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29 02 302 |
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Jul 1979 |
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DE |
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0 881 211 |
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Dec 1998 |
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EP |
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1 102 370 |
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Feb 1968 |
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GB |
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Primary Examiner: Manoharan; Virginia
Attorney, Agent or Firm: Novak Druce & Quigg
Claims
We claim:
1. A process for fractionating an amine-containing mixture which
comprises at least one amine, water, low-boilers and optionally
high-boilers, having step, (iii) and (iv) and optionally step (v):
(iii) extracting the amine-containing mixture with sodium hydroxide
solution, to obtain an aqueous, sodium-hydroxide-containing first
phase, and an aqueous-organic second phase which contains amine,
low-boilers and, where present, high-boilers, (iv) distilling the
aqueous-organic second phase in a distillation column having a
stripping part and an enrichment part, to obtain essentially
anhydrous amine as bottom-phase take off or sidestream takeoff in
the stripping part of the distillation column, an amine-water
azeotrope as sidestream takeoff in the enrichment part of the
column and a low-boiler fraction as overhead takeoff, and recycling
the amine-water azeotrope to the extraction step (iii), and (v)
optionally further purifying or fractionating the essentially
anhydrous amine.
2. A process as claimed in claim 1, wherein the amine-containing
mixture comprises high-boilers and the process further comprises a
step (ii) in which a high-boiler fraction is separated off from the
amino-containing mixture by distillation to obtain an
amine-containing remainder and the remainder is introduced into the
extraction step (iii).
3. A process as claimed in claim 2, wherein, in step (iv),
essentially anhydrous amine is produced as sidestream takeoff in
the stripping part of the distillation column and further
high-boiler-containing amine is produced as bottom-phase takeoff
and this bottom-phase takeoff is recycled to step (ii).
4. A process as claimed in claim 1, wherein the extraction step
(iii) is carried out in multiple stages as countercurrent flow
extraction in an extraction column having from 1 to 25 theoretical
plates.
5. A process as claimed in claim 1, wherein the distillation step
(iv) is carried out at a pressure of from 1 to 40 bar and at a
temperature of from -20 to 300.degree. C., and the distillation
column has from 3 to 80 plates.
6. A process as claimed in claim 1, wherein the amine-containing
mixture is a product mixture produced in a preparation of
dimethylpropylamine from dimethylamine and propionaldehyde in the
presence of hydrogen, or from dimethylamine and propanol.
7. A process as claimed in claim 1, wherein the amine-containing
mixture is a product mixture produced in a preparation of
piperidine or N-methylpiperidine from 1,5-pentanediol and ammonia,
or methylamine, respectively.
8. A process as claimed in claim 1, wherein the amine-containing
mixture is a product mixture produced in a preparation of
morpholine or N-methylmorpholine from diethylene glycol and
ammonia, or methylamine, respectively.
9. A process as claimed in claim 1, wherein the amine-containing
mixture is a product mixture produced in a preparation of
pyrrolidine or N-methylpyrrolidine from 1,4-butanediol and ammonia,
or methylamine, respectively.
10. A process as claimed in claim 1, wherein the process further
comprises a step (i) in which a low-boiler fraction is separated
off from the amine-containing mixture by distillation to obtain an
amine-containing remainder and the remainder is introduced into the
extraction step (iii).
11. A process as claimed in claim 1, wherein the amine-containing
mixture comprise; high-boilers and the process further comprises
steps (i) and (ii) in which a low-boiler fraction and a high-boiler
fraction are separated off from the amine-containing mixture by
distillation to obtain an amine-containing remainder and the
remainder is introduced into the extraction step (iii).
Description
The invention relates to a process for fractionating a mixture
which comprises one or more amines, water, low-boilers with or
without high-boilers.
In the reaction of ammonia, primary or secondary amines with
alcohols or with aldehydes in the presence of hydrogen, a reaction
product produced, inter alia, is water, which frequently forms an
azeotropic amine/water mixture with the product amine formed. In
addition, the product mixture comprises low-boilers having a lower
boiling point than that of the amine/water azeotrope, for example
unreacted ammonia, or starting amine, and high-boilers having a
higher boiling point than that of the product amine, for example
higher-molecular-weight byproducts.
GB 1,102,370 describes a process for extractive distillation of an
ethylenediamine/water mixture in which, in a first distillation
column, the ethylene/water crude mixture is evaporated and the
ascending vapor is brought into contact with aqueous sodium
hydroxide solution flowing in countercurrent. At the top of the
first column a low-water ethylenediamine/water mixture is obtained
which has an amine concentration above the azeotropic point, which
mixture is further distilled by simple rectification in a second
column. At the top of the second column, pure ethylenediamine is
obtained and at the bottom of the second column an
ethylenediamine/water mixture is obtained which is combined with
the crude mixture and recycled to the extractive distillation.
DE-A 29 02 302 describes a process for separating ethylamine
mixtures in which a diethylamine-, triethylamine-, ethanol-, water-
and possibly monoethylamine-containing mixture is extracted with
water and a water-immiscible solvent, an aqueous phase and a
water-immiscible phase being obtained. The two phases are separated
and further worked up by distillation. Water-immiscible solvents
used are n-butane, n-hexane and cumene.
DE-A 27 23 474 describes a process for fractionating a water-,
monoethylamine-, diethylamine- and triethylamine-containing
mixture, in which an essentially anhydrous mixture of
monoethylamine and diethylamine and triethylamine is separated off
by distillation and, by distillation, monoethylamine is separated
off from the anhydrous mixture of monoethylamine and
diethylamine.
EP-A 0 881 211 describes a process for preparing anhydrous
2-amino-1-methoxypropane in which, in an extraction step, a
2-amino-1-methoxypropane-containing aqueous reaction mixture is
admixed with sodium hydroxide solution, forming a
sodium-hydroxide-containing aqueous phase and a
1-amino-1-methoxypropane-containing phase, the aqueous phase is
separated off and, in a distillation step, the
2-amino-1-methoxypropane-containing phase is distilled, an
azeotrope of water and 2-amino-1-methoxypropane first being
produced, which is recycled to the extraction step, and then
anhydrous 2-amino-1-methoxypropane then being produced.
It is an object of the present invention to provide an improved
process for fractionating water-containing crude amine mixtures
from amine synthesis, which process is suitable for a multiplicity
of different crude amine mixtures.
We have found that this object is achieved by a process for
fractionating an amine-containing mixture which comprises one or
more amines, water, low-boilers and optionally high-boilers, having
the steps (i) to (v): (i) optionally separating off by distillation
a (first) low-boiler fraction from the amine-containing mixture,
(ii) optionally separating off by distillation a (first)
high-boiler fraction from the amine-containing mixture, (iii)
extracting the amine-containing mixture with sodium hydroxide
solution, producing an aqueous, sodium-hydroxide-containing first
phase and an aqueous-organic, amine-, (further) low-boiler- and
possibly (further) high-boiler-containing second phase, (iv)
distilling the aqueous-organic second phase, producing essentially
anhydrous amine as bottom-phase takeoff or sidestream takeoff in
the stripping part of the distillation column, an amine/water
azeotrope as sidestream takeoff in the enrichment part of the
column and a (further) low-boiler fraction as overhead takeoff, and
recycling the amine/water azeotrope to the extraction step (iii),
(v) optionally further purifying or fractionating the essentially
anhydrous amine.
The process is carried out continuously. Withdrawing a low-boiler
fraction as overhead takeoff from the distillation column in step
(iv) avoids enrichment of low boilers due to recycling amine/water
azeotrope to the extraction step (iii) in the continuous mode.
"Amine" is also taken to mean a mixture of a plurality of
amines.
Optionally, before the extraction step (iii), high-boilers can be
separated off (ii), preferably they are separated off.
Surprisingly, as a result, this avoids the unwanted formation of
solids in the extraction step (iii).
A first removal of low-boilers (i) can be provided upstream of the
high-boiler removal (ii). Preferably, low boilers are removed, in
particular if the amine synthesis employs an excess of starting
material amine.
Essentially anhydrous amines can be obtained in the distillation
step (iii) as bottom-phase takeoff or as sidestream takeoff in the
stripping part of the distillation column. Particular preference is
given to a process variant in which essentially anhydrous amine is
produced as sidestream takeoff in the stripping part of the column
and further high-boiler-containing amine is produced as
bottom-phase takeoff, with this bottom-phase takeoff being recycled
to the high-boiler removal (ii).
The essentially anhydrous amine produced in the distillation step
(iv) can be further purified or fractionated in a downstream
distillation step (v). Such a distillation step is required to
produce the pure amines, if the starting mixture comprises two or
more amines which, with water, form azeotropes having a very
similar boiling point. Examples of this are azeotropes whose
boiling points differ by no more than 10.degree. C.
Two embodiments of the invention are described in more detail
below.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1 and 2 illustrate the two embodiments of the process.
DETAILED DESCRIPTION OF THE DRAWINGS
With reference to FIG. 1, the reaction output of amine preparation
which is to be fractionated is fed as inflow stream 1 to a
low-boiler removal column a. Low-boilers are, for example,
unreacted starting material amine. The low-boiler removal column is
generally operated at a pressure of from 1 to 40 bar absolute,
preferably from 10 to 30 bar absolute, and at a temperature of
generally from 20 to 300.degree. C., preferably from 30 to
250.degree. C. The number of theoretical plates is generally from 3
to 80, preferably from 10 to 30.
At the top of the low-boiler column, a majority of the low-boilers
are produced as overhead takeoff stream 2, which can be recycled to
the amine synthesis. The bottom-phase takeoff stream 3 is fed to
the high-boiler removal column b having generally from 3 to 80,
preferably from 10 to 30, theoretical plates and distilled at a
pressure of generally from 0.15 to 40 bar absolute, preferably from
1 to 5 bar absolute, and at a temperature of generally from -20 to
300.degree. C., preferably from 30 to 250.degree. C. As
bottom-phase take off stream 4, high-boilers are produced which are
discharged from the process. High-boilers are, for example,
byproducts having a higher molecular weight than the desired
product amines. As overhead takeoff stream 5 an amine/water
azeotrope is produced which still comprises traces of low-boilers
and high-boilers. As a result of the high-boiler removal, the
solids formation does not occur in the downstream extractor c.
The overhead takeoff stream 5 is combined with the sidestream
takeoff stream 9 of the azeotrope removal column d and fed to the
extractor c. The extractor c can be of single or multistage design.
A single-stage extractor c is, for example, a single mixer-settler
extractor. Multistage extractors c are, for example, an extraction
column or extractor cascade. Suitable extraction columns are, for
example, packed columns, sieve-plate columns, cascade columns,
pulsed columns, rotary columns and centrifugal columns. An
extractor cascade is, for example, a plurality of series-connected
mixer-settler extractors which can also be constructed in a
space-saving manner as tower extractors or box extractors.
Preferably, the extractor c is multistage, particularly preferably
a countercurrent flow extraction column having generally from 1 to
25, preferably from 4 to 10, theoretical plates. These are
generally operated at a pressure at which all components of the
extraction mixture are above their boiling point. The temperature
is selected in such a manner that none of the components of the
extraction mixer is above its boiling point, and, in addition, a
viscosity of both phases is established at which dispersion of the
two phases is possible without problem. The temperature is
generally from 5 to 200.degree. C., preferably from 20 to
70.degree. C., for example from 40 to 50.degree. C. Sodium
hydroxide solution is added as inflow stream 6. Generally, the
concentration of the sodium hydroxide solution is from 1 to 75% by
weight, preferably from 25 to 50% by weight. After phase separation
the aqueous, sodium-hydroxide-containing phase is discharged from
the process as effluent stream 7.
The aqueous-organic, amine-containing phase is fed as stream 8 to
the azeotrope separation column d. The azeotrope separation column
generally has from 3 to 80, preferably from 10 to 30, theoretical
plates and is operated at a pressure of generally from 1 to 40 bar,
preferably from 2 to 8 bar, and at a temperature of from -20 to
300.degree. C., preferably from 50 to 120.degree. C. In the
enrichment part of this column an amine/water azeotrope is obtained
as sidestream takeoff stream 9 and is combined with the overhead
takeoff stream 5 of the high-boiler removal. Further low-boilers
are obtained as overhead takeoff stream 10. As bottom-phase takeoff
stream 11, anhydrous amine is obtained which can still comprise
traces of high-boilers. The bottom-phase takeoff stream 11 can be
further distilled in the distillation column c, with pure amine
being obtained as overhead takeoff stream 12 and other high-boilers
as bottom-phase takeoff stream 13.
With reference to FIG. 2, a variant of the abovedescribed process
is described. In this case, anhydrous amine is not taken off as
bottom-phase takeoff stream from the azeotrope separation column,
but as sidestream takeoff stream 12. As bottom-phase takeoff stream
11, an amine having an elevated content of high-boilers is taken
off, combined with the bottom-phase takeoff stream 3 of the
low-boiler removal and recycled to the high-boiler removal.
Preferably, the bottom-phase takeoff stream 11 is from 0.1 to 20%
by weight of the total of streams 11 and 12.
The sidestream takeoff stream 11 can be further fractionated in a
downstream purifying distillation column. This is necessary to
produce pure amines if two or more amines are present in the
starting mixture, which form with water azeotropes having very
similar boiling points. Examples of such mixtures are
N-methylmorpholine/N-ethylmorpholine/water,
pyrrolidine/N-methylpyrrolidine/water and
piperidine/N-methylpiperidine/water.
The starting mixtures to be fractionated by the process according
to the invention can vary greatly in their composition and
generally comprise, per mol of product amine, from 0 to 9 mol,
preferably from 0 to 3 mol, of low-boilers, from 1 to 10 mol,
preferably from 1 to 4 mol, of water and, based on the total of all
components of the starting mixture, from 2 to 20% by weight of
high-boilers.
Examples of starting mixtures to be fractionated by the process
according to the invention are: the product mixtures produced in
the preparation of dimethylpropylamine from dimethylamine and
propionaldehyde in the presence of hydrogen, or from dimethylamine
and propanol. These can comprise, as low-boilers, unreacted
dimethylamine and, formed from this by disproportionation,
monomethylamine and trimethylamine. If the preparation starts from
propionaldehyde, the starting mixture can comprise, as
high-boilers, the compounds 2-methylpent-2-enaldehyde,
2-methylvaleraldehyde, dimethyl(2-methylpent-2-enyl)amine and
dimethyl(2-methylpentyl)amine which are formed by the reaction of
two molecules of propionaldehyde and subsequent amination and/or
hydrogenation. the product mixture produced in the preparation of
piperidine from 1,5-pentanediol and ammonia. This mixture can
comprise unreacted ammonia as low-boiler. High-boilers which can be
present are 2-methylpentanediol, dipiperidinylpentane and
2-methylpiperidine. the product mixture produced in the preparation
of N-methylpiperidine from 1,5-pentanediol and methylamine. As
low-boilers, all of the abovementioned methylamines may be present.
High-boilers are, for example, the reaction products of
1,5-pentanediol with one or two molecules of dimethylamine. the
product mixture obtained in the preparation of morpholine from
diethylene glycol and ammonia. The low-boiler is ammonia, and the
high-boiler is, for example, dimorpholino diglycol. the product
mixture obtained in the preparation of N-methylmorpholine from
diethylene glycol and methylamine. Low-boilers which may be present
are all of the abovementioned methylamines. High-boilers are, for
example, the reaction products of diethylene glycol with one or two
molecules of dimethylamine. the product mixture produced in the
preparation of pyrrolidine from 1,4-butanediol and ammonia. The
low-boiler is ammonia, high-boilers are, for example, the products
formed by further reaction of the resultant pyrrolidine with
unreacted 1,4-butanediol. the product mixture produced in the
preparation of N-methylpyrrolidine from 1,4-butanediol and
methylamine. Low-boilers which may be present are all of the
abovementioned methylamines. High-boilers are, for example, the
reaction products of 1,4-butanediol with one or two molecules of
dimethylamine.
The invention is described in more detail by the example below.
EXAMPLE
The product mixture obtained in the synthesis of piperidine from
ammonia and pentanediol is treated by the process according to FIG.
1. The mass flow rate and composition of the starting mixture
(stream 1) and of the other streams occurring in the workup are
reported in the table below. The mixture is distilled at 21 bar in
a low-boiler removal column having 22 theoretical plates. At the
top of the column ammonia is taken off (stream 2). The bottom
temperature is 204.degree. C. The top temperature is 46.degree. C.
The bottom-phase discharge of the low-boiler column (stream 3) is
then distilled at 1 bar in a high-boiler removal column having 25
theoretical plates. At the bottom a stream is taken off (stream 4)
which principally comprises dipiperidinylpentane,
2-methylpiperidine and 2-methylpentanediol. The overhead takeoff
(stream 5) comprises water, piperidine and 2-methylpiperidine. The
bottom temperature is 176.degree. C. The top temperature is
95.degree. C. The overhead takeoff stream of the high-boiler
removal column is combined with the sidestream takeoff stream
(stream 9) of the azeotrope distillation column and fed to the
extraction column operating at atmospheric pressure and having 10
theoretical plates. The extraction is carried out at atmospheric
pressure with 50% strength by weight sodium hydroxide solution
which is added at the top of the extraction column. The bottom
temperature is 55.degree. C. The top temperature is 39.degree. C.
As organic phase, a low-water mixture of piperidine and
2-methylpiperidine, which has a residual water content of 2% by
mass, is taken off at the top of the extraction column (stream 8),
which is fed to the azeotrope distillation column having 18
theoretical plates. This operates at atmospheric pressure. The
bottom temperature is 113.degree. C. The top temperature is
95.degree. C. At the third plate from the top, the azeotrope
water/piperidine and traces of 2-methylpiperidine (stream 9) are
taken off in the sidestream takeoff and combined with the overhead
takeoff stream of the high-boiler removal. The bottom-phase takeoff
stream (stream 11) of the azeotrope distillation column is fed to
the purifying distillation column operating at atmospheric
pressure. At the top of the purifying distillation column there is
produced the product stream whose main component is piperidine
(stream 12). At the bottom a stream (stream 13) is separated off
which principally comprises 2-methylpiperidine. The bottom
temperature is 123.degree. C. The top temperature is 109.degree. C.
The process was run over a period of 40 days without solids
formation in the extraction column and without accumulation of
low-boilers.
TABLE-US-00001 TABLE Stream* 1 2 3 4 5 8 9 10 11 12 13 Water 1.136
0.000 1.136 0.000 1.136 0.054 0.050 0.004 0.001 0.001 0.000
NH.sub.3 2.755 2.755 0.000 0.000 0.000 0.000 0.000 0.000 0.000
0.000 0.000- Piperidine 2.507 0.000 2.507 0.003 2.505 2.606 0.105
0.009 2.492 2.480 0.0- 12 2-methyl- 0.104 0.000 0.104 0.104 0.000
0.000 0.000 0.000 0.000 0.000 0.00- 0 pentanediol 2-methyl- 0.084
0.000 0.084 0.044 0.040 0.040 0.000 0.000 0.040 0.003 0.03- 7
piperidine Dipiperidinyl- 0.098 0.000 0.098 0.098 0.000 0.000 0.000
0.000 0.000 0.000- 0.000 pentane Total 6.683 2.755 3.028 0.248
3.680 2.700 0.155 0.013 2.532 2.483 0.049 *Figures in kg/h
* * * * *